/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 2004,2005 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.sun.org.apache.xerces.internal.util;

import java.io.InputStream;
import java.io.IOException;
import java.io.Reader;

import com.sun.org.apache.xerces.internal.impl.ExternalSubsetResolver;
import com.sun.org.apache.xerces.internal.impl.XMLEntityDescription;
import com.sun.org.apache.xerces.internal.xni.XMLResourceIdentifier;
import com.sun.org.apache.xerces.internal.xni.XNIException;
import com.sun.org.apache.xerces.internal.xni.grammars.XMLDTDDescription;
import com.sun.org.apache.xerces.internal.xni.parser.XMLInputSource;

import org.xml.sax.ext.EntityResolver2;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

/**
 * <p>This class wraps a SAX entity resolver (EntityResolver2) in an XNI entity resolver.</p>
 *
 * @author Michael Glavassevich, IBM
 */
public class EntityResolver2Wrapper
    implements ExternalSubsetResolver {

  //
  // Data
  //

  /**
   * An instance of SAX2 Extensions 1.1's EntityResolver2.
   */
  protected EntityResolver2 fEntityResolver;

  //
  // Constructors
  //

  /**
   * Default constructor.
   */
  public EntityResolver2Wrapper() {
  }

  /**
   * <p>Creates a new instance wrapping the given SAX entity resolver.</p>
   *
   * @param entityResolver the SAX entity resolver to wrap
   */
  public EntityResolver2Wrapper(EntityResolver2 entityResolver) {
    setEntityResolver(entityResolver);
  } // <init>(EntityResolver2)

  //
  // Public methods
  //

  /**
   * <p>Sets the SAX entity resolver wrapped by this object.</p>
   *
   * @param entityResolver the SAX entity resolver to wrap
   */
  public void setEntityResolver(EntityResolver2 entityResolver) {
    fEntityResolver = entityResolver;
  } // setEntityResolver(EntityResolver2)

  /**
   * <p>Returns the SAX entity resolver wrapped by this object.</p>
   *
   * @return the SAX entity resolver wrapped by this object
   */
  public EntityResolver2 getEntityResolver() {
    return fEntityResolver;
  } // getEntityResolver():EntityResolver2

  //
  // ExternalSubsetResolver methods
  //

  /**
   * <p>Locates an external subset for documents which do not explicitly
   * provide one. If no external subset is provided, this method should
   * return <code>null</code>.</p>
   *
   * @param grammarDescription a description of the DTD
   * @throws XNIException Thrown on general error.
   * @throws IOException Thrown if resolved entity stream cannot be opened or some other i/o error
   * occurs.
   */
  public XMLInputSource getExternalSubset(XMLDTDDescription grammarDescription)
      throws XNIException, IOException {

    if (fEntityResolver != null) {

      String name = grammarDescription.getRootName();
      String baseURI = grammarDescription.getBaseSystemId();

      // Resolve using EntityResolver2
      try {
        InputSource inputSource = fEntityResolver.getExternalSubset(name, baseURI);
        return (inputSource != null) ? createXMLInputSource(inputSource, baseURI) : null;
      }
      // error resolving external subset
      catch (SAXException e) {
        Exception ex = e.getException();
        if (ex == null) {
          ex = e;
        }
        throw new XNIException(ex);
      }
    }

    // unable to resolve external subset
    return null;

  } // getExternalSubset(XMLDTDDescription):XMLInputSource

  //
  // XMLEntityResolver methods
  //

  /**
   * Resolves an external parsed entity. If the entity cannot be
   * resolved, this method should return null.
   *
   * @param resourceIdentifier contains the physical co-ordinates of the resource to be resolved
   * @throws XNIException Thrown on general error.
   * @throws IOException Thrown if resolved entity stream cannot be opened or some other i/o error
   * occurs.
   */
  public XMLInputSource resolveEntity(XMLResourceIdentifier resourceIdentifier)
      throws XNIException, IOException {

    if (fEntityResolver != null) {

      String pubId = resourceIdentifier.getPublicId();
      String sysId = resourceIdentifier.getLiteralSystemId();
      String baseURI = resourceIdentifier.getBaseSystemId();
      String name = null;
      if (resourceIdentifier instanceof XMLDTDDescription) {
        name = "[dtd]";
      } else if (resourceIdentifier instanceof XMLEntityDescription) {
        name = ((XMLEntityDescription) resourceIdentifier).getEntityName();
      }

      // When both pubId and sysId are null, the user's entity resolver
      // can do nothing about it. We'd better not bother calling it.
      // This happens when the resourceIdentifier is a GrammarDescription,
      // which describes a schema grammar of some namespace, but without
      // any schema location hint. -Sg
      if (pubId == null && sysId == null) {
        return null;
      }

      // Resolve using EntityResolver2
      try {
        InputSource inputSource =
            fEntityResolver.resolveEntity(name, pubId, baseURI, sysId);
        return (inputSource != null) ? createXMLInputSource(inputSource, baseURI) : null;
      }
      // error resolving entity
      catch (SAXException e) {
        Exception ex = e.getException();
        if (ex == null) {
          ex = e;
        }
        throw new XNIException(ex);
      }
    }

    // unable to resolve entity
    return null;

  } // resolveEntity(XMLResourceIdentifier):XMLInputSource

  /**
   * Creates an XMLInputSource from a SAX InputSource.
   */
  private XMLInputSource createXMLInputSource(InputSource source, String baseURI) {

    String publicId = source.getPublicId();
    String systemId = source.getSystemId();
    String baseSystemId = baseURI;
    InputStream byteStream = source.getByteStream();
    Reader charStream = source.getCharacterStream();
    String encoding = source.getEncoding();
    XMLInputSource xmlInputSource =
        new XMLInputSource(publicId, systemId, baseSystemId);
    xmlInputSource.setByteStream(byteStream);
    xmlInputSource.setCharacterStream(charStream);
    xmlInputSource.setEncoding(encoding);
    return xmlInputSource;

  } // createXMLInputSource(InputSource,String):XMLInputSource

} // class EntityResolver2Wrapper
